League of Legends (or LoL for short) is an action real-time strategy game developed and published by Riot Games, inspired by the popular Defense of the Ancients: All-Stars custom map for WarCraft III. It was first announced on October 7, 2008, and released on October 27, 2009. The game was in a closed beta from April 10, 2009, to October 22, 2009. It then transitioned to open beta until release. The game is a direct competitor to Dota 2.

Players are formed into 2 even teams of Champions, 3v3 or 5v5. Each team starts at opposing sides of a map in an area called the Spawning Pool, near what is called a Nexus. A match is won when either team's nexus is destroyed. To destroy a Nexus, each team must work through a series of Turrets. Turrets are often placed along a path to each base referred to as a Lane. Along the way, each player gains levels from killing the opposing team's champions and Minions (small NPCs that constantly spawn and attack the other team) and defeating neutral monsters (some of which grant buffs known as crests upon death). Completing objectives rewards players with gold which is used to purchase items.

The best League of Legends players compete in Riot Games' League of Legends Championship Series (or LCS for short). Twenty teams compete in two separate competitions in North America and Europe, with ten teams per continent. There are two splits per year. The League of Legends Challenger Series (CS for short) serves as a league that feeds into the LCS, with the bottom teams in the LCS from each split competing with the top teams from the CS to determine placements in the next split of the LCS and CS. The top teams of the LCS splits qualify for the League of Legends World Championship near end of the year, the largest tournament in LoL esports, where they compete for a multi-million dollar cash prize pool.

Riot's approach to creating a sustainable competitive scene is to provide players in the LCS with a salary, as opposed to raising the prize pool directly or via crowd-funding. As a result, League of Legends prize pools tend to be smaller, albeit still a substantial size.